Reset control aims at enhanced performance that cannot be obtained by linear controllers. The conventional reset control is simple for implementation by resetting some of its controller states to zero when its input meets a threshold. However, it is found that in some cases the enhanced performance of conventional reset control is still limited such as with only partial reduction of the overshoot in a step reference response. Thus, the stability analysis and design of the reset control system are extended, where the reset time instances are prespecified and the controller states are reset to certain non-zero values, which are calculated online in terms of the system states for optimal performance. Experimental results on a piezoelectric positioning stage demonstrate that the extended reset control can further reduce the overshoot and thus achieve shorter settling time than the conventional reset control. Moreover, robustness tests against various step levels, disturbance and sensor noise are presented.